I’m pretty new to 3d printing, so I’ll probably use all the wrong names for things… Anyway, I’ve been using my Ender 3 Pro for a couple of months, and it has been working wonderfully.

Out of the blue, it started under-extruding. I think that’s the term, anyway. It looks like it’s printing the layers very thin. I’ve attached a photo of the result of trying to print a 1mm thick circle.

Equipment details:

• Printer: Ender 3 Pro
• Slicer software: Ulimaker Cura 4.10.0
• Filament: PLA 1.75mm

I’ve been trying to research how to troubleshoot this problem, and have tried the following:

• Made sure the bed is level and the nozzle isn’t too close
• Cleaned the nozzle
• Reset all slicer settings, in case I had inadvertently changed something.
• Replaced the nozzle tip (it came with a spare)
• Replaced the bowden tube
• Replaced the bowden tube couplings
• Adjusted the tension spring on the extruder motor

If I heat the nozzle, I can manually push filament through without much resistance, so I’m confident there is no clog.

If I put pressure on the filament as it’s feeding in, it seems to print a bit heavier. But whenever it retracts while I’m doing that, I can feel it push back strongly enough that I don’t think the extruder gear (not sure if that’s what it’s called) is slipping, or that the extrusion motor is weak. Though my confidence isn’t as high on those points.

My next guess is to replace the extruder with something like this: Redrex Upgraded Aluminum Bowden Extruder. If replacing the extruder sounds like the right move, I’d love recommendations on a good one to buy. That one is just one of the first results that shows up in a search.

Any suggestions? Thanks for any help!